My L-29 454 1999 k2500 runs a maximum of 32 degrees at light throttle, basically almost coasting. Under light throttle 10-15% it drops to mid to low 20's. seems incredibly conservative. Has any experimented with increasing timeing to gain fuel mileage? Thinking there is alot left to improve upon. Under heavy towing or just cruising, I have never experienced knock retard. Just thought I'd ask. Thanks Ron B.

there is mileage and power with a retune of the factory ecu. call ed wright at fast chip. hes been in this busines longer than anyone and really knows his stuff. google fast chip

I have a '95 S10 4.3 TBI that when I bought it got 14 MPG city and 16MPG highway. Now, after tuning, it gets 19 city and 20 highway with the only mods bieng a cold air intake, exhaust and a very mild cam from an S10 Extreme. I've been tuning GM EFI since '99 and I guarantee 25HP and 10% MPG increase over factory and that is just on the first try. If I can tune to your driving style, the MPG increase can be as high as 40% on some vehicles although it takes many hours of datalogging and tuning to achieve optimum results.

After tuning, the wifes '03 Flex-Fuel Tahoe is a blast to drive on 105 octane E85. :D

With the right tools, there are many improvements that can be made to the factory ECU.

Has anyone tried using the timeing similar to a naturally aspirated big block? Like a total of 40 plus in a light load cruise situation. Thanks for the replys so far. Ron B.

The beauty of GM EFI is that you can tune the engine for optimal timing at every RPM and load. Since timing is computer controlled, you can forget old school methods and theories and give the engine exactly what it wants and through datalogging you can verify results.

There are many factors that affect engine timing. Octane rating, compression ratio, cam specs all affect timing but the most important is cumbustion chamber design. Todays "fast burn" combutsion chambers are far more efficient than even performance heads of the '70's and '80's. They make more power with less timing and you should always run the least amount of timing that gives maximum power. For example if your engine produces max power at 32 deg. of timing and power stays the same at 35 deg., then you should set it at 32 and leave it.

To answer your original question, EFI tuning has moved far beyond trying old school timing methods.